1. Field of the Invention
This invention relates to safety systems for miners operating in an underground mine. More particularly, this invention relates to a toxic gas removal and air conditioning system for providing safe and breathable air to occupants of a miner survival chamber when outside atmosphere contains potential harmful gases.
2. Background Discussion
Events such as floods, nuclear radiation accidents, explosions, fires, chemical spills, terrorist toxic gas attacks, and many other such hazards, can require that humans in the affected areas take refuge. Underground mines in particular present a host of such hazards. There are numerous risks inherent in underground mining operations: fires, cave-ins, methane or coal-dust explosions, flooding, asphyxiation, poisonous gasses in the mine atmosphere, and so forth.
When any person must seek refuge from an event such as those described above, most especially when miners are trapped underground, their survival may depend upon their ability to find temporary shelter inside a survival refuge chamber until the danger has passed, or until rescue responders find and extract the miners from the chamber. Specially designed survival chambers are typically placed at various locations in a mine, and miners are trained and drilled to know these locations. In this way, if a mine accident occurs, the miners can quickly find and enter the nearest survival chamber, and they can occupy the chamber until it is safe to exit.
Since survival chambers are air-sealed to prevent the intrusion of dangerous gases that may be present in the mine atmosphere outside the chamber, the miners have only four possible sources of oxygen (O2). These include:)1(the O2 that was present in air in the chamber before it was sealed, which can include O2 found in compressed air tanks inside the chamber; (2) the O2 that can be introduced into the chamber another source that is outside the chamber, including O2 found in (a) air piped into the chamber from outside compressed air tanks; (b) the mine atmosphere immediately surrounding the chamber; and (c) air piped into the chamber from a source outside the mine.
The amount of time that a miner (or group of miners) can survive in a survival chamber is dependant, at least in part, on the amount of O2 available inside the chamber. Since the rescue operations can take days (even weeks), it is critically important that survivable O2 levels be present in the air inside the chamber for the longest period of time possible.
It is important to recognize that the air inside a sealed chamber occupied by humans becomes contaminated over time, due primarily to the occupants' exhaling air that introduces waste gases, principally additional carbon dioxide (CO2) into the chamber's atmosphere.
When the ratio of CO2 to O2 is too large, survival chamber occupants can suffer CO2 poisoning. To prevent this condition, gas monitoring and air-scrubbing systems are employed within the chamber to remove excess CO2 from the chamber atmosphere.
Any such system must be intrinsically safe in a mine environment. It must also be very rugged, due to the hostile environment characteristic of underground mines. Additionally, it must be capable of surviving the forces present inside the chamber when an explosion occurs outside the chamber. Such a system must also be intrinsically safe (that is, unable to generate unsafe conditions, such as generating a spark, or emitting an explosive or poisonous gas in sufficient quantity to present a danger).
Such a system would optimally detect any loss of externally-supplied power and automatically begin operation when such a condition is detected, so that it would not be necessary for miners to manually start or operate the air scrubber.
Further, the noise generated by a monitoring or scrubbing system should be minimized. This is because miners occupying the survival chamber have no choice but to listen to system noise for extended periods of time, and the adverse psychological impact of stress from long-term exposure to noise can be significant.
In order for a rescue team to verify that gas monitors and air-scrubbers are operating (without entering the survival chamber), the systems should have means to wirelessly communicate system conditions to communications and control systems outside the chamber.
In the solutions of known current art, there are no gas monitoring or air-scrubbing systems for use in survival chambers in underground mines that meet all of these requirements. There is thus an urgent and critical need for such a system to significantly improve the ability for miners trapped in a mine to survive.